Harper Lee, the Southern novelist who achieved lifelong fame with her first—and for many decades, only—book, "To Kill a Mockingbird," died Feb. 19 in Monroeville, Alabama. She was 89.

Ms. Lee spent her final year surrounded by a renewed tornado of notoriety. She made headlines in 2015 when it was announced a new book penned by her, "Go Set a Watchman"—only her second in 55 years—would be published. The controversial publication was first advertised as a "found" manuscript by her lawyer. It was later revealed to be a rejected first draft of "To Kill a Mockingbird," written before the more famous book came out. Critics were not approving of the volume, or even of the idea that a lesser book by the aging Ms. Lee had been allowed to reach readers. But "Watchman" commanded a two million dollars in advance purchases anyway.

Then, last month, it was announced that a new stage adaptation of "Mockingbird," written by Aaron Sorkin, would reach the Broadway stage in 2017-18, directed by Bartlett Sher. A previous stage version of the book, authored by Christopher Sergel, had already been mounted by several regional theatre across the U.S. over the last decade of so.

Despite her slim output, and dislike of being interviewed, Harper Lee was one of the most famous American authors of her generation, and, indeed, of all time. She achieved it all through "To Kill a Mockingbird," a partly autobiographical novel of small-town Southern life in the 1930s. Almost immediately upon publication, in 1960, the book became not only a perennial bestseller, and taught regularly in schools, but a cherished classic of American literature. It won the Pulitzer Prize the next year. A popular 1962 film of the novel, starring Gregory Peck, only burnished the book’s reputation and fame.

Fellow Southern writer Horton Foote wrote the screenplay for the film. Ms. Lee’s was pleased, saying, "I think it is one of the best translations of a book to film ever made."

The leisurely paced, gentle drama told of a lawyer of quiet integrity, Atticus Finch, as he attempts to properly raise his two children, Jem and Jean Louise (called by everyone "Scout"), following the young death of his wife. When he takes on the defense of a poor young black man who is accused of raping a white woman, the trial disrupts the town’s, and his family’s, rhythms, and opens Scout’s eyes to the prejudice and injustice around her. The town in the novel was based on Monroeville, AL, where Ms. Lee was born April 28, 1926. One of her childhood friends was future novelist Truman Capote, who would appear at the character "Dill" in "Mockingbird." They remained friends as they grew up, and Ms. Lee assisted Capote in her research for his book "In Cold Blood." Ms. Lee is a character in "Capote" and "Infamous," two films about Capote. She is played by Catherine Keener in the former and Sandra Bullock in the latter. Lee is also the model for a character in Capote's first novel, "Other Voices, Other Rooms," which came out in 1948.

Aside from "Watchman," and a few essays, Ms. Lee published nothing further after "Mockingbird." She become—along with Margaret Mitchell, Ralph Ellison, Ross Lockridge, Jr. and John Kennedy Toole—one of American great one-hit-wonder novelists. For years, the public anxiously waited for a second book, but, despite various false starts and rumors, nothing materialized.